Cable closure

ABSTRACT

Cable closures and methods are provided for enclosing a cable. The cable closure includes two half shells together forming an enclosed space for housing a cable, and a sealing strip positioned between peripheral regions of the half shells, at least one of the shells having a removable portion to provide a cable entry port. A cable sealing device may be positioned at the cable entry port such that a seal is provided between the sealing strip and each half shell and a cable entering through the port.

RELATED APPLICATIONS

The present application is a National Phase application ofPCT/GB99/03454 filed on Oct. 19, 1999 and published in English, whichclaims priority from Applications GB 9824447.8 filed on Nov. 6, 1998 andGB 9913441.3 filed on Jun. 9, 1999.

FIELD OF THE INVENTION

This invention relates to a cable closure, by means of whichenvironmental protection may be provided around a cable splice,termination or other cable portion. The invention may be used with powercables, CATV cables or telephony or other communications cables. Theinvention is likely to find most use in protecting splices in, andterminations of, optical fibre cables.

BACKGROUND OF THE INVENTION

The use of closures for environmental sealing of cable splices is ofcourse well known. Cables are produced in finite lengths and thereforelengths of cable frequently need to be joined together. The function ofa closure is to provide a seal that bridges the jackets of the splicedcables. A closure may also provide other functions in addition toenvironmental protection, such as mechanical protection and axial-pullstrength. Closures may be used around simple end-to-end splices betweencables, but frequently more complex splices require sealing. Forexample, a large cable containing many conductors (by which term Iinclude optical fibres as well as electrical conductors) may be splitinto two or more smaller cables. Ultimately, a cable will be effectivelyterminated where it is broken down to single conductors or small groupsof conductors. Such terminations also require cable closures to protectthem.

It is frequently necessary to install a cable closure around a cablesplice (or termination) where access to ends of the cables is notavailable. In such circumstances the closure clearly cannot bepermanently of closed cross-section: the closure needs to be “wrappedaround” the cables, rather than slid onto the cables from one end. Thisterm “wrap around” derives from cable closures that were formed fromflexible sleeves or longitudinally-slit tubes. It is, however, a generalterm that merely refers to the capability of installation around a cableat some point between its ends. Thus, the term includes substantiallyrigid half shells that are assembled around the splice. The shells maybe hinged or otherwise linked together by moulded-in strips or by tapesor living hinges etc. The term “half shells” does not imply anyparticular shape, and the two half shells may be different or generallysimilar in shape to one another. Thus, each half shell will have aperiphery that abuts the periphery of the other half shell, and eachwill have a hollow body portion, roughly semi-circular in cross-section,so that when the two half shells are brought together they define aroughly rectangular or circular cylindrical enclosed space within whichthe splice will lie. Half shells may, however, differ from one another,so that one might be described as a base plate, and the other as acover. These terms “wrap around” and “half shells” are well-known in theart.

Many cable closures have been proposed that make use of half shells.Unfortunately, many problems remain. The performance requirements of aclosure are very difficult to meet. The problem arises largely because aclosure must be very quick and easy to install, usually with unskilledlabour, and under difficult conditions, but must meet very stringentperformance specifications. As a general rule a cable closure isexpected to have a life time comparable to that of the cables which itprotects, typically twenty or more years. Cables are generally situatedout of doors and are subjected to extremes of temperature and humidity.Various tests have been devised to mirror this long-term performance.Although different tests are applicable to different cables in differentsituations, typical tests involve pressurisation of the closure whilstit is subjected to temperature cycling, often under wet or humidconditions. A closure is expected not to leak for a certain number ofsuch cycles. Clearly, closures of the half shell design start out at adisadvantage because a seal must be provided between the half shells aswell as between the incoming and outgoing cables and each half shell. Aparticularly severe problem arises at the region where a seal betweenthe half shells meets a seal between the cables and each half shell.This region is known as the “triple point”. It can therefore be seenthat design of such a closure is a difficult matter.

The difficulties are, as usual, increased by the need for low cost. Therequirement for low cost means that it is not possible to supplydifferent designs of closure for each cable size and for each splice ortermination configuration. Thus, a single design of closure must be ableto accommodate, for example, a simple in-line splice between two cables,a butt splice between two cables (where the two cables lieside-by-side), and various configurations, such as “one in-two out”where one cable enters one end of a closure and two leave at an oppositeend. In order to accommodate a range of splice configurations, one maydecide to provide a closure that has four cables seals, two at each end.Cable seals are, unfortunately, expensive and such a closure would needto be provided with four such seals. Each of these seals would need tobe capable, not only of sealing to an incoming cable, but also becapable of being closed in case the full compliment of cables was not tobe employed. The present invention provides a particularly simple andelegant solution to these problems.

Before the invention is described in detail it may be worth noting someprior art closures of the half shell type. U.S. Pat. No. 5,322,973discloses an aerial closure for protecting a cable splice. It has acentral header portion and wing-like housing segments that may enclosethe splice. The wing-like housing segments may be raised to provideaccess to the splice. Each end of the closure has a seal assembly forsealingly engaging the ends of the incoming cables. These assemblieshave concentrically circular and corrugated features thereon so that anappropriately size hole may be cut to allow entry of 1, 2 or 3 cables ofvarious sizes.

U.S. Pat. No. 4,805,979 discloses a fibre optic splice closurecomprising a base to which a cable may be anchored, and a cover whichoverlies the base. Seals are provided around the cables at the positionwhere the base meets the cover.

U.S. Pat. No. 4,492,816 discloses half shells for forming a cablesplice. Half shells have flanges which abut one another in the assembledconfiguration. The adjacent flanges define a duct into which sealingmaterial in the form of a paste may be introduced. Opposite ends of theresulting closure are provided with jaws which clamp against theincoming cables. Two jaws define between them a chamber whichcommunicates with the sealing duct by means of a channel formed aroundthe entire periphery of a jaw adjacent to the chamber.

EP 0543350 discloses a cable enclosure formed from a base and a coverwhich are secured together by bolts through flanged portions thereof.Various cable guide sections are located at the interface between thebase and the cover.

GB 1260273 discloses a housing for electrical connections, whichcomprises a cylindrical central part and end parts that form a sealbetween the central housing and each incoming cable. The end parts aremoulded to provide a number of cable entry ports. The ports areinitially blind. The extreme ends of the ports are cut off as and whenrequired to allow cables to pass through. The ports are heat-shrinkableso that after insertion of a cable a port can be shrunk to make sealingcontact with it.

U.S. Pat. No. 5,109,467 discloses an optical fibre interconnect cabinetin the form of a box with a lid. The side walls of the box are providedwith slots which can receive removable blanks. With the blanks in place,and the lid closed, the box is sealed. With the lid open, a blank can beremoved to provide a port for cable entry.

Whilst each of those prior art designs provides some of the benefitsthat I now seek, each unfortunately suffers from one or more problems.For example, some of the designs are not fully “wraparound”, some arenot suited for environmental protection out of doors, some are toocomplex and expensive, and some do not provide the desired flexibilityin terms of cable size and/or cable configuration.

I have now designed a cable closure that can provide excellent sealingfor a variety of cable configurations, and which allows quick and simpleinstallation.

SUMMARY OF THE INVENTION

Thus, the invention provides a cable closure comprising:

1) two half shells that together form an enclosed space for housing acable (more particularly some part of a cable such as a termination orsplice),

2) a sealing strip (preferably formed of a resilient material such as arubber or a synthetic elastomer) positioned between a peripheral regionof each half shell such that, when the half shell are brought together,said space can be sealed;

3) at least one of the shells having a removable portion that, whenremoved, provides a cable entry port between the two shells, the sealingstrip providing a seal between that portion and the other shell(preferably a removable portion of the other shell when, as ispreferred, each shell is provided with a removable portion).

The invention also provides a method of enclosing a cable, whichcomprises:

a) providing a cable closure as defined above;

b) removing said removable portion;

c) removing that part of the sealing strip that provided a seal betweensaid removable portion and said other shell; and

d) bringing the half shells together around the cable such that a cablepasses through the port provided by removal of the removable portion.

One of the half shells may have the form of a base and the other theform of a cover, or each half shell may have a generally hollow regionwhich together form said space. Thus, each half shell may be, forexample, substantially semi-circular, semi-rectangular orsemi-elliptical, in cross-section such that when the half shells arebrought together a generally cylindrical space is formed that issubstantially circular, substantially rectangular particularly withrounded corners or substantially elliptical in cross section. In generalit will be a desirable for each half shell to be formed, for example bymoulding, from a single piece of material. Each half shell may, however,comprise two or more parts joined together, but this has thedisadvantage that seals between those parts must be provided.

Where I refer to the sealing strip being positioned between “peripheral”regions of the half shells I simply mean that the sealing strip istowards the outside of the shells, although it need not of course be atthe extreme edge. In general, the sealing strip will lie betweenperipheral flanges or edge walls of the half shells, which flanges oredge walls may extend outwardly of the sealing strip for example toprovide means by which the half shells can be held together. Such meansmay comprise a bolt that passes through holes in the flanges or edgewalls. It will be understood that it is desirable that such holes beprovided outwardly of the sealing strip since otherwise a leak path intothe splice case could exist via the holes.

I refer above to the space within the closure being capable of beingsealed when the shells are brought together. This is because someadditional sealing means or sealing operation may be required. However,in general, sealing between the half shells will result directly fromthe half shells being brought together with the sealing strip betweenthem, although some fixing means such as the bolts mentioned above maybe required to prevent the half shells from separating particularly ifthe closure is to be pressurised. Thus, the sealing strip preferablyfollows a substantially closed path around the periphery of the halfshells. The sealing strip is preferably in one piece along its length,and may be continuous.

Complete sealing of the space within the closure will of course usuallyrequire some additional seal to be provided between incoming cables andthe ports through which they enter. In general, a cable sealing devicewill be provided that is of annular shape, the outside surface of theannulus sealing against the internal surface of the port, and the innersurface of the annulus sealing against the external surface of thecable. Thus, the cable sealing device effectively fills any gap betweenthe cable and the port through which it enters. The design of such cablesealing devices presents its own difficulties. These difficulties resultin part from the need to be able to seal to cables of different sizes,since there will be some size variation even between cables of onenominally standard size. Furthermore, the cable sealing device needs toseal not only to the cable and to the surrounding half shells (wherethey define the port), but also to the sealing strip. This is the“triple point” problem referred to above. The cable closure of theinvention is able to overcome this problem in a particularly elegantway. Thus, I prefer that at least one of the half shells (preferablyboth) is shaped to define, adjacent and inwardly of the port, a chamberfor receiving a cable sealing device; and that the sealing strip runalong opposed longitudinal sides of said chamber such that, when thesealing device is in the chamber, the strip at each said side contactseach half shell and the cable sealing device.

In preferred designs of the closure at least two said removable portionsare provided side-by-side. A particularly preferred closure is designedto provide four cable entry ports, two side-by-side at each end. Theclosure may be supplied to the customer with one (or more) ports alreadyopen, that is with one (or more) potential removable portions beingabsent. The precise design will of course depend on the cableconfigurations possessed by the customer. Therefore, I prefer theclosure to have at least two side-by-side ports, whether or not both ofthe ports in question have removable portions that would close them. Iprefer that at least one of the half shells be shaped to defineadjacently inwardly of each said port a chamber for receiving a cablesealing device; and that the sealing strip run along opposedlongitudinal sides of each chamber such that, when a sealing device isin each chamber, the sealing strip at each said side contacts each halfshell and the respective sealing device; and that separate portions ofthe sealing strip run between the chambers along each of the adjacentlongitudinal sides. An alternative is possible; it would be possible fora single portion of sealing strip to run between the two side-by-sidechambers. That single portion would therefore be shared by the twochambers.

That alternative arrangement is, however, less satisfactory because itwould need to be rather wide, or the two chambers to be rather close, ifthat single portion of sealing strip were to contact both sealingdevices.

These separate portions of sealing strip are preferably joined togethertowards an inward end of the chambers. In that way the seal iscompleted. Also, such a design allows the two half shells to be joinedtogether by the means of, for example, bolt that passes through holes inthe half shells; the holes would be positioned between the separateportions of sealing strip and outwardly of the position at which theyare joined. In this way, the holes for the bolt do not provide a leakpath into the splice case.

I prefer that the removable portion that gives rise to the cable port bean integral part of a half shell, although it may initially be separateand later bonded or otherwise sealing fixed to the half shell. The portpreferably is formed substantially equally in each half shell, andtherefore each half shell preferably has a said removable portion, bothof which are to be removed to define the port.

In order that the cable sealing device form a good seal to the halfshells, I prefer that the chambers (which will usually be defined by theinside surfaces of each half shell) be wholly concave in cross-section.Clearly, any irregularities in the curvature of the chamber will make areliable seal difficult. If the cable sealing device is to seal a singlecable then the external surface of the sealing device will preferably besubstantially circular. However, I prefer that each sealing device becapable of sealing at least two cables, more preferably two cablesside-by-side. In this case the cable sealing device need not be ofsimple annular shape, but may have, say, the shape of two annuliside-by-side with the roughly triangular spaces between them filled in.Overall, in cross-section the cable sealing device may be substantiallyelliptical. However, a circular cross-section may still be appropriate,particularly if four cables are to be sealed. Clearly, the chambers forthe sealing device should have a cross-section or shape that correspondsto the sealing device, and will in general therefore be substantiallycircular or substantially elliptical in cross-section. The chambers maybe provided with some fixing means such as one or more lugs or flangesto prevent axial movement of the sealing device.

The cable sealing device may be of the general design and constructiondisclosed in WO 90/05401 (N. V. Raychem S. A.). Thus, the sealing devicemay comprise along an axis thereof first and second end parts and asealing material between them, the first and second ends parts and thesealing material each allowing a cable to pass through them, the devicehaving means to bring the first and second end parts together therebyputting the sealing material under compression axially, and causing itto be displaced radially to contact a cable therein and the chambertherearound. In general, the first and second ends parts and the sealingmaterial will be provided with an axial hole through which the cable canpass. Also, the first and second end parts and the sealing material maybe provided with a radial slit that extends from their outer surface tosaid hole, which slit can be opened out to allow the sealing device tobe “wrapped around” the cable. A preformed hole need not be provided inthe sealing material since it may be possible to rupture the sealingmaterial by pushing the cable through it.

The means that bring the first and second end parts together maycomprise a nut and a bolt, one of which is fixed to one end part and theother of which bears against the other end part such that when they arerelatively rotated the parts move together. Resilient means such as aspring, preferably a coiled compression spring, may be provided to biasresiliently together the first and second parts, thus maintaining thesealing material under compression during the service life of theclosure.

The sealing material preferably comprises a gel, but other materialssuch as rubbers or mastics may be used. A gel is a liquid-extendedpolymer composition preferably having a cone penetration value (measuredby a modified version of ASTM D217) within the range from 30 to 400(10⁻¹ mm), and an ultimate elongation (measured by ASTM D412) greaterthan 100%, and preferably also with substantially elastic deformation tothe elongation of at least 100%. The composition may containthree-dimensional cross-linked molecular formations, or merely behave asif it contains such molecular formations.

Useful compositions may be provided comprising at least 500 preferablyat least 1000 and preferable not more than 5000 parts by weight of anextender liquid per 100 parts by weight of block copolymer or otherpolymer. Preferred block copolymers are those based on styrene andolefines such as ethylene and butylene. Particularly useful gels may bemade using styrene-ethylene-butylene-styrene block copolymers such asthose marketed by Shell under the trade name “Kraton”. Such gels aredisclosed in WO 90/05401 referred to above.

The sealing strip may be made of any suitable material, particularly aresilient material such as a rubber or synthetic elastomer. Examplesinclude solid or hollow rubber, rubber foam and rubber gel. Suchmaterials may be used in combination with other materials, for example amastic, gel or other sealant. In this way, one component may provide aresilient bias and another component may be more deformable and be usedto make intimate contact with the various surfaces. For example, a strip(of any suitable cross-section) of resilient material may be positionedin a channel or groove in one or both of the half shells. If desired, asealing strip may be positioned in each half shell so that the twosealing strips contact one another when the two half shells are broughttogether. I prefer that the sealing strip or strips be continuouslengthwise (before a part is removed after removal of the removableportions of the half shells) in the region of the removable parts andalong the sides of the chambers adjacent those removable parts. Morepreferably I prefer that the sealing strip (or each strip if one ispositioned initially in each half shell) be unbroken along its lengthfor the whole closure. However, in certain circumstances it may bedesirable to use separate strips at each end of the closure.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be further described with reference to theaccompanying drawings, in which:

FIG. 1 is a perspective view of part of a cable closure showing two halfshells separated;

FIG. 2 is similar and shows in more detail a sealing strip;

FIGS. 3a and 3 b are plan views showing a sealing strip before and afterpart of it is removed;

FIGS. 4a and 4 b show installation of a cable sealing device and closureof the half shells;

FIGS. 5a, 5 b, 5 c and 5 d show a cable closure enclosing splices ofvarious cable configurations; and

FIGS. 6A-C; FIGS. 7A-B; FIGS. 8A-D; FIGS. 9A-B and FIG. 10, illustrate anew sealing strip for use in the closure of the invention, and designsof half-shells preferred for the new sealing strip.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

FIG. 1 shows a cable closure, although the cables are omitted forclarity. The closure has two half shells, 1,2 which when broughttogether form an enclosed space 3. In the design illustrated the halfshell 2 is slightly curved, but is largely planar, and half shell 1 hasa dome-like shape. The closure contains optical fibre splice trays 4pivotally mounted on a stepped base 5. The generally planer design ofhalf shell 2 results in easier access to the splice trays 4 when thehalf shells are separated.

A sealing strip 6 is shown running around a peripheral region 7 of halfshell 2.

The half shells have removable portions 8, 9 which can be removed by anysuitable means such as by means of a saw 10, or knife, or cutting wire11. When the portions 8 and 9 are removed, cable entry ports 12 areprovided. Chambers 13 are provided adjacent, preferably immediatelyadjacent, and inwardly of the ports. The chambers are provided forreceiving cable sealing devices 14, one of which is illustrated. It canbe seen that the cable sealing strip 6 runs along opposing longitudinalsides 15, 16 and 17, 18 of the two chambers. Thus, when the sealingdevice 14 is positioned in the chamber 13, as is the case in the lowerchamber illustrated, the strip at each longitudinal edge 17, 18 contactsnot only the half shells, 1, 2 but also the sealing device 14.

The sealing device 14 has first and second end parts 19, 20 betweenwhich is positioned a sealing material 21. The end parts and the sealingmaterial have holes 22 through which cables pass to enter the closure. Ameans 23, which may carry a screw thread is used to bring together thefirst and second end parts, 19, 20, to put the sealing material 21 undercompression. The means 23 bears against the first end part 19 and itsscrew thread engages a screw thread fixed relative to end part 20. Iprefer that means 23 carries a female screw thread and part 20 carries amale screw thread, although the situation may be reversed. Resilientbiassing means such as a compression coil spring 24 is provided so thatwhen the screw threads have been advanced a suitable amount, the springmaintains the sealing material 21 under compression. I prefer that thebias of the spring act over a sufficient distance such the sealingmaterial may creep or otherwise be displaced to some extent without theresilient bias being lost.

It can be seen that when first and second end parts 19 and 20 arebrought together the sealing material will be displaced to some extentin a radial direction to cause it to contact, and therefore to seal to,the internal walls of the half shells 1, 2 that define the chamber 13.The sealing material 21 will also be radially displaced inwardly to sealto cables extending through holes 22. The triple point referred to aboveexists at region 25 where the sealing material 21 and sealing strip 6meet. This is a critical area which provides problems in many prior artclosure designs. The present arrangement of the sealing strip inrelation to the removable portions 8, 9 and to the chambers 13 allowthese problems of the prior art to be overcome. Thus, in a simple andelegant fashion, a closure can be provided that is initially closed andthat allows ports to be created and cables to be sealed within them.

The half shells illustrated in FIG. 1 shows various other features, suchas strengthening ribs and flanges allowing the two halves to boltedtogether. Other means may be provided to bring and/or to hold the twotogether, for example latches, wedges or channels.

The sealing strip is illustrated further in FIG. 2. FIG. 2 is anexploded perspective view showing the sealing strip positioned betweenthe half shells, 1, 2. The wall of half shell 2 can be seen to beprovided with means, in this case a ridge, for location of sealing strip6. The path taken by the sealing strip 6 can clearly be seen to followthe opposing longitudinal sides, 15, 16, 17 and 18 of the two chambers13.

Thus, it can be clearly seen that separate portions of sealing strip(corresponding to opposed longitudinal sides 16 and 17) run between thechambers. It was mentioned above that this arrangement is preferred toan alternative arrangement where a single length of sealing materialruns between the two chambers. It can be appreciated that it will bedifficult for such a single length of material to bridge two sealingdevices 14 (not shown in FIG. 2). These two portions of the sealingstrip 6 are joined together at 26 to complete the seal (the join ispreferably nominal, and the strip is preferably of a continuous lengthat least in this region). This arrangement is particularly advantageoussince it allows the two half shells, 1, 2 to be joined together withmeans of a bolt or other fixing device that passes through holes 27. Itcan be seen that the holes 27, being outward of the sealing strip,cannot provide a leak pass into the closure.

FIGS. 3a and 3 b show in plan view the sealing strip 6 before and afterremoval of that part 28 thereof that originally provided a seal betweenopposing removable portions 8, 9.

FIGS. 4a and 4 b show assembly of the closure, although again cables areomitted for clarity. In FIG. 4a the half shells 1, 2, the sealing strip6, and the cable sealing device 14 are shown separated. One cable entryport 12 is shown open, and a second potential cable entry port remainsclosed by removable portions 8, 9. The open port 12 may have beenprovided by removal of removable portions similar to those illustratedat 8, 9 or the half shells may have been manufactured with that port 12open. Since at least one port will always be required it is notnecessary that all ports initially be closed unless the installerrequires full flexibility as to which ports are to be closed. In FIG. 4bthe cable sealing device 14 has been placed in the chamber 13 and thehalf shells have been brought together.

FIGS. 5a, 5 b, 5 c and 5 d show alternative cable splice configurations.FIG. 5a shows a one-in one out in-line splice. FIG. 5b shows a buttsplice between two cables, both of which enter the closure through asingle port. In this arrangement, if the half shells were provided withone port originally open, then installation in this case would notrequire removal of any of the removable portions. It can be seen thatthe two cables make use of the two holes in a single cable sealingdevice. Alternatively, a two cable butt splice could be protected usingboth of the two side-by-side ports. Other cable configurations are shownin FIGS. 5c and 5 d. Further flexibility can be achieved by using a plugwithin one of the holes in the cable sealing device 14, and that is whathas been done in FIG. 5a.

FIGS. 6 to 10 illustrate a new sealing strip for use in the closure ofthe invention, and designs of half-shells preferred for the new sealingstrip. The sealing strip preferably comprises an elastomeric materialsuch as a rubber, and is preferably extruded. FIG. 6A shows intransverse cross-section a part of the closure illustrated in FIG. 1.Half-shells 1, 2 are shown slightly separated before being closed aroundsealing strip 6. The peripheral region 7 of the lower half-shell 2 canbe seen. Each of the half-shells 1, 2 has a groove 29 a, 29 b, forreceipt of part of the sealing strip 6. Grooves 29 a and 29 b arepreferably substantially similar in shape to one another, morepreferably mirror images. Each groove preferably has a recess 30 thatextends away from the plane separating the two half-shells. Such recesspreferably extends substantially perpendicular to that plane. Thesealing strip 6 preferably has extensions, generally in the form of lipsor flanges 31 that extend above and below the main body of the sealingstrip and that extend into the recesses 30. As a result the sealingstrip becomes trapped in the half-shells, 1, 2 against lateral movement(i.e. horizontally, or across the page, in FIG. 6a). This can bedesirable where it is necessary for the sealing strip 6 to be open tothe inside of the closure in order that it contact sealing material 21on sealing device 14 (see FIG. 1) at the so-called triple point 25. Itcan be desirable for sealing strip 6 to be thus located in order toavoid its displacement where a sealing device 14 has not been installed.Furthermore, the sealing strip 6 may be provided with one or more meanssuch as a barb or other projection 32 by means of which the lip orflange 31 may be made an interference fit in recess 30. In this way thesealing strip 6 can be installed in one of the half-shells, 1,2 andretained in position whilst the other half-shell is brought intoposition. In particular, I prefer that the flanges and recesses be soarranged that the sealing strip be predictably retained in a given oneof the half-shells and therefore be released from the other half-shellwhen the half-shells are separated. This can be achieved by one flangebeing a tighter interference fit in one half-shell than the other flangeis in the other half-shell. Alternatively or additionally one only ofthe flanges and half-shells could interlock. I prefer that the recessesin each half-shell be substantially identical and that this preferentialretention result from one only of this flanges being sized to result inits retention in a recess.

FIG. 6b illustrates a short length of a sealing strip 6. The arrowsindicate its preferred lateral flexibility. This ability is furtherillustrated in FIG. 6c which shows the extent to which may usefully bebent when installed in a closure such as that as illustrated in FIG. 1.The longitudinal edges of 15, 16, 17 and 18 of the chambers 13 at FIG. 1are marked on FIG. 6c. It is preferred that the strip 6 be able to passaround curves of bend radius 10 mm or less.

FIGS. 7a and 7 b show the sealing strip installed between half-shells 1,2 after those half-shells have been brought together. In FIG. 7A thesealing strip 6 is shown forming a seal to sealing material 21 of asealing device 14 as illustrated in FIG. 1. The area of intersection,the triple point, is labeled 25. In FIG. 7b, however, the sealing device14 is absent and as a result the edge of the sealing strip 6 appears atthe interior wall of the closure, unconstrained by sealing material 21.It is this situation that the lips 31 are of particular benefit toretain the sealing strip in position. This situation will arise, forexample, where a closure is to be used around fewer than its maximumpossible complement of cables. In that case the removable portions 8, 9will not, in general, have been removed.

FIGS. 8a, 8 b, 8 c and 8 d show installation of sealing strip 6 inhalf-shell 2, and the formation of a closure by bringing into positionthe other half-shell 1.

FIGS. 9a and 9 b compare two designs of half-shells 1, 2 and sealingstrip 6. In FIG. 9b the half-shells and the sealing strip have beendesigned such that the displacement of material of the sealing stripwhere the half-shells are brought together is such (say about 20%thereof) that the recesses 29 a, 29 b are substantially filled by thematerial constituting the sealing strip. In FIG. 10 a sealing strip 6having a hollow interior 34 is used. This hollow interior may beprovided in order to reduce the compression force required to installthe seal.

In general, therefore, I prefer a sealing strip that has one or moreprojections, preferably running along its length and preferablycontinuously, that restrict any tendency of the sealing strip to bedisplaced into or out of the closure along a plane that separates thehalf-shells 1,2. Correspondingly, I prefer that the half-shells beprovided with grooves 29 a, 29 b for receipt of the sealing strip andthat those grooves are provided with recesses 30 extended away from theplane between the half-shells.

The foregoing is illustrative of the present invention and is not to beconstrued as limiting thereof. Although a few exemplary embodiments ofthis invention have been described, those skilled in the art willreadily appreciate that many modifications are possible in the exemplaryembodiments without materially departing from the novel teachings andadvantages of this invention. Accordingly, all such modifications areintended to be included within the scope of this invention as defined inthe claims. In the claims, means-plus-function clauses are intended tocover the structures described herein as performing the recited functionand not only structural equivalents but also equivalent structures.Therefore, it is to be understood that the foregoing is illustrative ofthe present invention and is not to be construed as limited to thespecific embodiments disclosed, and that modifications to the disclosedembodiments, as well as other embodiments, are intended to be includedwithin the scope of the appended claims. The invention is defined by thefollowing claims, with equivalents of the claims to be included therein.

What is claimed is:
 1. A cable closure comprising: a) half shells thattogether form an enclosed space for housing a cable; b) a sealing strippositioned between a peripheral region of each half shell to seal theenclosed space; at least one of the half shells having a removableportion that, when removed, provides a cable entry port between the twohalf shells, the sealing strip providing a seal between the removableportion of the at least one of the half shells and the other of the halfshells; and wherein at least one of the half shells is shaped to define,adjacent and inwardly of said cable entry port, a chamber for receivinga cable scaling device; and in which the sealing strip runs alongopposing longitudinal sides of said chamber such that, when the cablesealing device is received in the chamber, the sealing strip at eachsaid longitudinal side contacts each half shell and the cable sealingdevice.
 2. A cable closure according to claim 1 having at least two ofsaid removable portions side-by-side to provide at least twoside-by-side of said cable entry ports.
 3. A cable closure according toclaim 1 having at least two side-by-side removable portions, in which atleast one of the half shells is shaped to define, adjacent and inwardlyof each said removable portion, a chamber for receiving a cable sealingdevice, one of which is said chamber defined inwardly of said cableentry port; and in which the sealing strip runs along opposinglongitudinal sides of each chamber such that, when a cable sealingdevice is in each chamber, the sealing strip at each said side contactseach half shell and the respective cable sealing device, separateportions of the sealing strip running between the chambers along each ofthe adjacent longitudinal sides.
 4. A cable closure according to claim3, in which the separate portions of the sealing strip running betweenthe chambers along each of the adjacent longitudinal sides are joinedtogether at a position towards an inward end of the chambers, the halfshells each having a hole therethrough for receipt of means to hold themtogether, the holes being positioned between the separate portions andoutwardly of the position at which the separate portions are joined. 5.The cable closure of claim 1 wherein the sealing strip contacts thecable sealing device at a region intermediate longitudinal ends of thechamber.
 6. A cable closure comprising: a) half shells that togetherform an enclosed space for housing a cable; b) a sealing strippositioned between a peripheral region of each half shell to seal theenclosed space; at least one of the half shells having a removableportion that, when removed, provides a cable entry port between the twohalf shells, the sealing strip providing a seal between the removableportion of the at least one of the half shells and the other of the halfshells; and wherein the removable portion is an integral part of thehalf shell, a border of the removable portion being defined at least inpart by at least one of a line of weakness or a visual indication.
 7. Acable closure comprising: a) half shells that together form an enclosedspace for housing a cable; b) a sealing strip positioned between aperipheral region of each half shell to seal the enclosed space; atleast one of the half shells having a removable portion that, whenremoved, provides a cable entry port between the two half shells, thesealing strip providing a seal between the removable portion of the atleast one of the half shells and the other of the half shells; andwherein the half shells are shaped to define, adjacent and inwardly ofsaid cable entry port, a chamber for receiving a cable sealing device,the chamber having a cross-section that is substantially wholly concave.8. A cable closure comprising: a) half shells that together form anenclosed space for housing a cable; b) a sealing strip positionedbetween a peripheral region of each half shell to seal the enclosedspace; at least one of the half shells having a removable portion that,when removed, provides a cable entry port between the two half shells,the sealing strip providing a seal between the removable portion of theat least one of the half shells and the other of the half shells; andhaving, adjacent and inwardly of said cable entry port, a chamber forreceiving a cable sealing device; the cable closure additionallycomprising said cable sealing device.
 9. A cable closure according toclaim 8, in which the cable sealing device comprises along an axisthereof first and second end parts and a sealing material between them,the first and second end parts and the sealing material each allowing acable to pass through them; the cable sealing device having means tobring the first and second end parts together thereby putting thesealing material under compression axially, causing the sealing materialto be displaced radially to contact a cable therein and the chambertherearound.
 10. A cable closure according to claim 9, in which thesealing material comprises a gel.
 11. A cable closure according to claim9, in which the cable sealing device has means for allowing at least twocables to pass therethrough.
 12. A method of enclosing a cable, themethod comprising: a) providing a cable closure having two half shellspositioned adjacent each other to define an enclosed space for housingthe cable with a sealing strip postioned between a peripheral region ofeach of the half shells, at least one of the half shells having aremovable portion defining a cable entry port therein when removed, thesealing strip having a portion providing a seal between the removableportion and the other of the half shells when the removable portion isnot removed; b) removing said removable portion; c) removing thatportion of the sealing strip that provided a seal between said removableportion and said other shell of the half shells; and d) bringing thehalf shells together around the cable such that a cable passes throughthe port provided by removal of the removable portion; and wherein thecable closure is shaped to define, adjacently and inwardly of said port,a chamber for receiving a cable sealing device, and in which the sealingstrip runs along opposing longitudinal sides of said chamber, whereinthe step of bringing the half shells together around the cable furthercomprises causing the sealing strip running along opposing longitudinalsides of said chamber to contact each half shell and the cable sealingdevice.
 13. The method of claim 2 wherein the sealing strip contacts thecable sealing device at a region intermediate longitudinal ends of thechamber.